[BNM] [OT] BT ISDN : REDUX

Crosbie Fitch bnmlist@brightonnewmedia.org
Fri Sep 20 12:05:01 2002


> -----Original Message-----
> From: bnmlist-admin@brightonnewmedia.org
> [mailto:bnmlist-admin@brightonnewmedia.org]On Behalf Of Dave Phelan
> Sent: Friday, 20 September 2002 11:27am
> To: bnmlist@brightonnewmedia.org; bnmlist@brightonnewmedia.org
> Subject: RE: [BNM] [OT] BT ISDN : REDUX
>
> Surely not!
> HH is ISDN2e, with a terminal adaptor built into the wallbox.

Yes, but in plain parlance that translates to 'different beastie', i.e. it's
like saying the XBox is just a PC with a good graphics card. However, HH &
XBox are supplied with a particular configuration and usage in mind -
distinct from the flexibility of the underlying system in the package.


> With any ISDN2 service, you can have multiple numbers, allocated to
> different devices on the S-bus. HH takes a couple of numbers
> and routes
> calls to them to the two analogue sockets. ISDN has 2
> B-channels (64kbps
> digital) and a 16kbps D channel for signalling.

Yup.

> You could run modem calls over these "analogue lines" as per
> any normal
> POTS circuit. You could use one for voice and one for
> analogue data, and
> the exchange would transit them according to the network as
> voice (I forget
> the actual CCITT#7 terms). The TA encodes the analogue data
> into a B channel.

Yeah... but then why get HH if you're just going to use analogue modems?
Maybe it's close to the same price as a second line, but I don't think it's
cheaper.

>
> You could use a real ISDN phone plugged into the ISDN socket
> (S-bus) That
> would send digital voice.
> You could plug an ISDN card in your PC into the S-bus and use
> one or two
> B-channels for digital data.

Thanks for all that extra techie info.

> How BT charges for HH, I don't know though. I'm just a techie.

Yes, the charging issue is the critical thing.

If you really want to get techie you could tell us if ISDN identifies the
difference between voice and data calls on the digital channels?  I vaguely
recall there is such identification. However, I wouldn't be surprised if you
still don't get free ISDN voice calls even though they can be identified
(and very unlikely for 2 channel voice). In other words, I reckon BT charges
based on the number, and not the DATA/VOICE tag of the call.